THE success of Doctor Who and Torchwood will spawn a succession of spin-off shows, it was predicted yesterday.

Yesterday, the BBC drama Spooks became the latest programme to have a spin-off announced, echoing the growing stable of Doctor Who programmes, which also feature Torchwood and the Sarah Jane Adventures.

The new show, with the working title Rogue Spooks, features new, young MI5 recruits in a "super-secret unit" which follows its own rule book.

The spin-off is being created by the same team behind the original popular MI5 drama, featuring Peter Firth and Anna Chancellor, which draws eight million viewers.

Paul Murphy, a television critic for TV Quick, said Rogue Spooks is mirroring Torchwood, featuring John Barrowman as Captain Jack, that is moving to BBC2 after breaking viewing records.

Mr Murphy said, "As soon as I heard about the new special unit operating to a different rule book, I thought how Rogue Spooks was doing for Spooks what Torchwood has done for Doctor Who.

"I have seen a lot of television and film and as a child and an adult, nothing has come close to Doctor Who when it comes to mind-blowing concepts. And whatever character you like best, everyone can identify with the Doctor, who acts as a positive role model for many people.

"Obviously getting a spin-off series is a measure of the success of a show and boils down to the quality of the idea. It is a way of giving an audience more of what they like without dressing it up as the same thing.

"With Torchwood, there was a hope that Doctor Who fans would come along for the ride.

"Adults watching Doctor Who and enjoying the jokes that go over the children's heads get an adult version in Torchwood, where there is gratuitous sex and some violence."

Created by Doctor Who writer Russell T Davies, Torchwood is produced by a team working at BBC Wales headquarters in Llandaff, Cardiff, the city where the series is set.

Up to four million watch the high-octane sci-fi thriller every week over its various showings.

The storyline follows a team of modern-day investigators as they use alien technology to solve alien and human crimes.

Rogue Spooks was announced at the BBC3 winter-spring 2007 season launch yesterday.

BBC3 controller Julian Bellamy said, "Torchwood is moving to BBC2, which is wonderful for BBC2 and Torchwood.

"We are developing a new show. It's in the pretty advanced stages and hopefully we'll see it in a few months."

Meanwhile Doctor Who is predicted to be the biggest Christmas TV audience draw since the heyday of Only Fools and Horses, with its festive episode The Runaway Bride, featuring Catherine Tate. The episode can be seen at 7pm on Christmas Day.

Earlier that day, at 1pm on BBC1 is Doctor Who Confidential: Music and Monsters, which goes behind the scenes at the recent concert at the Wales Millennium Centre in aid of Children in Need. It features music from the series performed by the BBC National Orchestra of Wales. The entire concert will be available on the "red button" on Christmas Day.